Club G40 Forum

Hi all,

I've recently bought a G of a friend of mine, he seems to think this issue is caused by the map but I just want a second opinion before I splash out on a new map!

Basically, if I keep at low revs and light throttle it drives fine. If I drive hard and keep it over 2500 it drives fine. The problem is after using full throttle or high revs, once you try cruise at say 2000rpm in 5th is judders and cuts constantly. If I pull over, turn the car off and on then it's fine, until I open it up again.

Any help would be appreciated, I've emailed PPP also.

If it helps im running 65mm pulley, cammed, toothed belt, 250cc, fmic, full engine back system etc.

Thanks a lot.

what map does it have in it?

I'll try find out exactly what chip it has, I only know its chipped and not custom.

Just spoke to him, It's a PPP chip.

presume it's one to suit 250cc injectors?

also, do you know the spec of the cam that's installed?

Im waiting for the chip code, it's a Newman Fast road cam.

Do you think this problem is the chip/map?

Thanks for your help.

but what spec is the cam? is it suitable for a g40?  "fast road" doesn't mean anything.  you'll need to specs for (at least) the duration of the cam to know if it's suitable.

If the chip is a suitable one for 250cc injectors then I doubt it's that unless it is damaged.  see what PPP come back with

Ah ok, it's 264/268.

right ok, that's not really suitable for a g40 then,. that's a GT cam.  You want to swap that for a standard G40 cam.  Even if it's not the cause of this issue it'll be causing a loss of power.

Really? I didnt know that.  ???

I have the original g40 cam, is it actually worth the effort of fitting? Or is it only worth it if I buy a proper uprated g40 one?

Thanks again, appreciate this.

I'd just put the standard cam back in.  There's not much gain to be had from fitting a different cam to a g40 engine when it's using the g40 supercharger.  And people generally go for a 256/272 or thereabouts cam.

Thanks mate. It is on a r1 glader so no fancy eaton or turbo!

Gonna give PPP a call after work.

Hi had a similar problem that turned out to be bad conection to knock sensor.it too cleared after ignition was turned off and back on.

Really? I'll try that first then.

Thanks

There's something wrong with your email, our replies to you just bounce.

Which one of our chips is it? (If you're not sure, tell me who you bought the car from and I'll look it up).
What's your full engine specification?
When did the running problem start?

It sounds like a much more fundamental problem than the chip. I also have no record of selling a chip to someone with a 264/268 cam in a G-ladered G40, so I assume that the engine spec has been changed since the chip was fitted?

It's also worth following the advice in this guide:
http://www.polog40.co.uk/forum/index.php/topic,214.0.html (http://www.polog40.co.uk/forum/index.php/topic,214.0.html)

Check the basics first, and go from there.

Thanks for the reply.

if you can confirm the make of the cam, I may be interested in a swap, as it might be suitable for my turbo conversion. I have a piper 272 cam which was made for a polo G40 with a G-Lader, its been fitted but never used and I have the original reciept for it.

It's a Newman 264/268 G40 fast road cam.

Also Before the cam gets swapped tonight back for the standard g40 cam, will it be a noticeable difference or is it not worth the time to change it?

Thanks

Obviously at odds with some of what's been said already, but I've a Newman "fast road" cam fitted and am quite pleased with the noticeable mid range pick-up. Newman advertise this cam specifically for the G40 and aren't pushing it for it's top end power. At 264/268 it can't be all that far away from the original cam's dwell and they've probably not altered lift very much if at all. I wouldn't write it off too soon.

Ok, I'm starting to get somewhere now. It looks and seems like its the ignition timing. The knock sensor is fine, I've done most of the basic diagnostic checks and all is well.

I spoke to the VW specialist who fitted the chip and he confirmed this was after all other mods. Running issues started pretty much instantly after this and we're thought it just needed fine tuning to solve.

Can anyone think of any other reasons before I get another map?

Thanks

What injectors does it have in it?
Have you checked the fuel pressure?

There Bosch ones I think. 250cc

Disconnected that blue sensor tonight and it still did it do reconnected. The lead running into it is labeled as "Knock" from when whoever put the engine in did the looms. It's a 3 prong plug. Possible it's in the wrong place? Looks like the wire runs past the inlet. If it is wrong where should it go?

Thanks

Blue temp sender should have a blue 2-pin connector going to it.
Knock sensor has a 3-pin connector, and the wiring harness is shielded cable, so it's easy to identify.
Check what's plugged in to your throttle body switches (white connector), and what's plugged into the CO pot/air temp sensor unit in the boost pipe.

The one on the pipe at the very top and back of the bay (assuming its the blue one as has a blue circle on it) is a 3 pin connector and has a lead labeled knock, it's a thick black wire which runs down past the fuel rail.

I'll have another look at what you said.

Thanks alot

I don't know if this is possible but looks like the co2 pot on the boost pipe has the knock plugged into it. Where should it be connected?

I'll try swap them round.

Thanks for your help

knock sensor bolts to the back of the block - but often the end has a 'holder' which is bolted to the inlet manifold

Thanks Pete.

The Knock sensor comes off the block and into the port on the boost pipe, theres one lead on the inlet bracket and that is a 2 pin one.

I'll go have another look.

The throttle has the white one.

Thanks.

Biggest help would be if someone knows what the wire/connector looks like that should go into co2 pot

it's just a black 3 pin connector.  The only other thing it'd fit into would be the throttle body but the connector for that is white so you dont mix them up.

Right!

Followed the wires back,

The knock was connected to the air sensor and the air sensor wires the knock!

The knock wasn't attached to inlet was just flapping around..

Swapped them over so now knock sensor goes to knock port and attached it to the bracket on the inlet. Also attached air sensor to air sensor..

Fingers crossed for when I drive home!

All solved!!!!!

Runs sooooooo smooth now!

Well happy.

Thanks for the help lads!

So when the VW specialist said it was the chip at fault, maybe it was when they plugged stuff back in wrongly!?  ;)

Haha yeah! But to be fair he knows his stuff so I doubt it was him.

Thanks a lot for all the help Andy.

Gonna have to start all over again soon when I put the turbo on no doubt!